The present invention relates to novel polysaccharides, a process for producing polysaccharides, uses of the polysaccharides and a strain producing the polysaccharides. The novel polysaccharides of the present invention may be used in various fields, for example, as a humectant, a film-forming agent, an emulsifier, a foam stabilizer, a water-retaining agent and a cement admixture.
Japanese Patent Application Laid-Open (Kokai) No. 63-156707 (1988) proposes a cosmetic composition containing hyaluronic acid as a humectant. The humectant, when used in cosmetics, serves for mitigating stimulus from the outside and for protecting the skin from becoming rough, and also improves the touch to the skin of the cosmetics. Generally, a humectant used as a cosmetic material is desired to have a moisture retention within the range of 10 to 50% under an ordinary environmental condition with a relative humidity of 40 to 80%. It is also required that its moisture retaining ability should be scarcely affected by the change of relative humidity (Fragrance Journal, special No. 9 "Science of Humectant", 1988, page 34, etc.).
However, hyaluronic acid has a serious defect that its moisture retaining ability is unstable and tends to be influenced by ambient humidity.
As a result of extensive search for a material having excellent moisture retaining ability, the present inventors have found that novel polysaccharides obtained by using a novel microorganism have excellent moisture retaining ability which is hardly influenced by ambient relative humidity. It has been also found that the novel polysaccharides have other useful properties. The present invention has been achieved on the basis of these findings.